Engine starter gearing



sept. 25, 1951 J. E. BUXTON 2,569,401

ENGINE STARTER GEARING Filed June 2, 1950 A ORNE Y Patented Sept. 25,1951 'ferries Claims 1 fsilheapresent. invention relates' toenginerstarter gearing; andvmore.I particularly tofth'atity'pe offidrive. which engages .an engine gear automatical- .s1-lywhenthestarting-motoriis energizedgfand' disengages whentheengineistarts.

.".tIt is kan objectsot the present invention to provide a novel enginestarter drive which is eiicient and reliablein'oper'ation, small insize, and simple fand economicalzin construction.

It is another object to provide suchaidevice inlv cluoling an. `elasticconnection which is arranged to slip when overloaded so as to protectthe drive from-excessive stresses.

` Itis-another objectto--provide such 'a device in which the elasticconnection is axially yieldable to assist in securing proper meshing ofthe gearing in case of tooth abutment between the drive pinion andengine gear.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation partly broken away and in section of apreferred embodiment of the invention showing the parts in idleposition; and

Fig. 2 is a similar view showing the parts in cranking position.

In Fig. l of the drawing there is illustrated a power shaft i on which ascrew shaft 2 is xedly mounted as by means of a cross pin 3 which isretained by a thimble 4 seated against a shoulder 5 on the screw shaft.A pinion 6 is slidably journalled on the power shaft for longitudinalmovement into and out of mesh with a gear 'I of the engine to bestarted.

Means for actuating the pinion from the'screw shaft is provided,comprising a control nut 8 threaded on the screw shaft and seatedagainst a shoulder 9 formed at the termination of the threads of thescrew shaft. A cylindrical member II having a radially inwardly directedange I2 is xedly connected to the pinion 6 as indicated at I3. Thecontrol nut 8 has a radial ange I4, and a spring member I5 is seated atone end on the control nut 8 against the ange I4, and at its other endwithin the cylindrical member I I against the ange I2. The centralconvolutions of the spring I5 are normally spaced from each other asindicated at I6 so as to make the spring longitudinally compressible.

The dimensions of the parts are such that the' spring engages theinterior of the cylindrical member Il and the exterior of the nut 8 withsuicient friction to transmit normal cranking loads.

flThe-spring'is so`-3Wou'nd, as indicated, that when #crankingLtorquefi`s-y `transmitted therethrough it "fete'nding'to relievethefrictional engagementbetween the spring and the cylindrical member II*sthatslippage takes place upon predetermined l overload/oft thevvdrive.

thelcontroliiut-andvlhas 'i-ts' open end rig-idlyconnected?to-thefcylindrical'vmember II in anysuitable way, as shown ati8. The barrel `jmer'nber has a shoulder I9v which normally engages the`"fthe."spri-n'gi I-5-un'der initial longitudinal lcompression betweenthe anges I4 and I2.

Barrel I1 has a terminal flange 2| resting on the power shaft I andpositioned to engage the end of the screw shaft 2 when the drive is incranking position. Preferably a thrust ring 22 is interposed to reducewear and to define the meshed position of the pinion 6.

Means normally maintaining the drive in idle position is provided in theform of an anti-drift spring 23 located within the barrel, bearing atone end against the thrust ring 22 and at its other end seated onthethimble 4 against a flange 24 thereof.

Means for limiting the compression of spring I5 is provided in the formof a spacing ring or cylinder 25 located within the barrel I1 betweenthe ange I4 of the control nut and a thrust ring 26 which bears againstthe end of the cylindrical member I I, so as to limit the travel of thecontrol nut toward the pinion 6.

In operation, starting with the parts in the positions illustrated inFig. 1, rotation of the power shaft I in the direction of the arrow (a)by the starting motor, not illustrated, causes the control nut 8 to betraversed to the right, which longitudinal movement is transmittedthrough the spring l5 to the cylindrical member Il, pinion 6 and barrelI1. Should the teeth of pinion 6 abut against the teeth of engine gear1, the spring I5 is longitudinally compressed by the control nut 8 untilsufficient torque is built up to index the pinion teeth into registrywith the tooth spaces of the engine gear, whereupon the pinion issnapped into initial-mesh with the engine gear by expansion of thespring I5, and the meshing movement of the pinion proceeds until themovement of the ange 2I is arrested by engagement of the thrust ring 22against the end of screw shaft 2.

The movement of the control nut 8 is continued until the flange I4engages the stop ring 25, at

which time the spring I is compressed firmly between the flanges I4 andI2, as shown in Fig. 2. Torque is then built up and transmitted throughthe spring I5 to rotate the pinion 6 and crank the engine. Should theinitial torque due to the inertia of the parts exceed a predeterminedoverload, the spring I5 wraps down slightly, relieving its frictionalconnection with th'e interior of the :cylindrical member Ii, thuspermitting slippage to take place until the excessive torque isdissipated; whereupon cranking proceeds normally without slippage.

When the engine starts, the acceleration of the pinion `6 by the enginegear I returns the par-ts to idle position with the assistance of theanti-drift spring 23, the backward movement of the control nut 8 beingarrested by the shoulder 9 on the screw shaft. When this engagementtakes place, the torque transmitted by the momentum of `the overrunningparts tends to unwrap the spring I5 which permits the spring to slip onthe control nut v8, and thus cushion the impact and prevent reboundingof the parts such as might cause undesired engagement of the pinion `6with the engine gear 1. v

Although but one embodiment of the invention has been shown anddescribed in detail, it will be understood that various changes may bemade in the precise design and arrangement of the parts withoutdeparting from the spirit of the invention.

I claim:

1. In an engine starter drive a power shaft, a screw shaft xed thereon,a pinion slidably jour- 4 nalled on the power shaft for movement intoand out of mesh with an engine gear, a cylinder fixed to the pinion, acontrol nut on the screw shaft, a coiled spring tightly engaging theperiphery of the nut at one end, and at its other end frictionallyengaging the interior of said cylinder, and a barrel member xedlyconnected at one end to said cylinder and having a flange at its otherend positioned to engage the end of the screw shaft when the pinion isin fully meshed position.

2. An engine starter drive as set forth in claim 1 in which the controlnut and cylinder are provided with radial anges engaging the ends of thespring, and the barrel is provided with a shoulder normally engaging thecontrol nut flange and thus maintaining the spring under initialcompression.

3. An engine starter drive as set forth in claim 2 in which the medialportion of the spring is provided With longitudinally spacedconvolutions rendering the spring endwise compressible.

4. An engine starter drive as set forth in claim 3 including means forpositively limiting the end- -wise compression of the spring.

JAMES E. BUXTON.

REFERENCES CITED UNITED STATES PATENTS Name Date Brockway June 14, 1932Number

